Exemplary embodiments of the present invention relate to an apparatus and method for taking up slack in a vehicle seat belt. More particularly, the present invention relates to a quick acting clutch for a seatbelt retractor.
Vehicles are provided with a seat belt and a seat belt retractor. Once the seat belt has been extended or unwound and a tongue is engaged into a latching or buckle device, it is desirable to retract or wind up an excess amount of the seat belt webbing.
Vehicle seat belts are also provided with an automatic winding device that, upon sensing of a predetermined condition will wind up a predetermined amount of slack or amount of seat belt webbing during a predetermined activation event (e.g., a massive deceleration or vehicle conditions sensed before an accident). This device employs a motor, which is energized to wind up the seat belt. During operation, a pretension signal will be sent to a motor of the retractor to retract a portion of the seat belt when an imminent danger or predetermined condition is detected.
Upon receipt of the pretension signal, the seatbelt retractor will respond by quickly tensioning the belt to a predetermined level and thereafter a pyrotechnic pre-tensioner and inflatable cushion deployments will follow if an event (e.g., collision) occurs. Some of the features of a seatbelt retractor are: it removes seat belt slack when an imminent danger is detected; and the seatbelt retractor will pull and hold an occupant in a designated position prior to the collision occurring. In addition, the seatbelt retractor is configured to work in harmony with a pyrotechnic pre-tensioning device in order to maximize the distance between the belted occupant and other parts of the vehicle.
If the imminent danger is avoided and no longer present (e.g., collision avoided), the seatbelt retractor is configured to reset itself and remain on a standby mode for the next pre-tensioning signal. In order to engage and disengage the motor from the spool containing the seat belt webbing a clutch mechanism is required to allow the motorized mechanism to i) engage and turn the spool on the seatbelt retractor when the motor receives an electrical signal from a control module, and to ii) disengage from the seatbelt retractor for normal everyday use, wherein extraction and retraction effort on the webbing is at a low comfortable level.
Accordingly, it is desirable to provide a clutch mechanism that quickly engages and disengages in response to sensed vehicle conditions.